SDP - Zero copy bcopy support

SDP - Zero copy bcopy support

This patch adds zero copy send support to SDP.  Below 2K transfer size,
it is better to bcopy.  With larger transfers, this is a net win on
bandwidth.  Latency testing is yet to be done.

                     BCOPY        BZCOPY
   1K  TCP_STREAM  3555 Mb/sec  2250 Mb/sec
   2K  TCP_STREAM  3650 Mb/sec  3785 Mb/sec
   4K  TCP_STREAM  3560 Mb/sec  6220 Mb/sec
   8K  TCP_STREAM  3555 Mb/sec  6190 Mb/sec
  16K  TCP_STREAM  5100 Mb/sec  6155 Mb/sec
   1M  TCP_STREAM  4630 Mb/sec  6210 Mb/sec

Performance work still remains.  Open issues include correct setsockopt
defines (use previous SDP values?), code cleanup, performance tuning,
rigorous regression testing, and multi-OS build+test.  Simple testing to
date includes netperf and iperf, ^C recovery, unload/load, and checking
for gross memory leaks on Rhat4u4.

Signed-off-by: Jim Mott <jim@mellanox.com>